ring-buffer: remove unneeded get_online_cpus
Impact: speed up and remove possible races The get_online_cpus was added to the ring buffer because the original design would free the ring buffer on a CPU that was being taken off line. The final design kept the ring buffer around even when the CPU was taken off line. This is to allow a user to still read the information on that ring buffer. Most of the get_online_cpus are no longer needed since the ring buffer will not disappear from the use cases. Reported-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Steven Rostedt <srostedt@redhat.com>
This commit is contained in:
Steven Rostedt
Родитель
59222efe2d
Коммит
8aabee573d
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@ -1561,15 +1561,11 @@ void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu)
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{
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struct ring_buffer_per_cpu *cpu_buffer;
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get_online_cpus();
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if (!cpumask_test_cpu(cpu, buffer->cpumask))
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goto out;
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return;
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cpu_buffer = buffer->buffers[cpu];
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atomic_inc(&cpu_buffer->record_disabled);
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out:
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put_online_cpus();
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}
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EXPORT_SYMBOL_GPL(ring_buffer_record_disable_cpu);
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@ -1585,15 +1581,11 @@ void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu)
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{
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struct ring_buffer_per_cpu *cpu_buffer;
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get_online_cpus();
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if (!cpumask_test_cpu(cpu, buffer->cpumask))
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goto out;
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return;
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cpu_buffer = buffer->buffers[cpu];
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atomic_dec(&cpu_buffer->record_disabled);
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out:
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put_online_cpus();
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}
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EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu);
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@ -1605,17 +1597,13 @@ EXPORT_SYMBOL_GPL(ring_buffer_record_enable_cpu);
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unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu)
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{
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struct ring_buffer_per_cpu *cpu_buffer;
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unsigned long ret = 0;
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get_online_cpus();
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unsigned long ret;
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if (!cpumask_test_cpu(cpu, buffer->cpumask))
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goto out;
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return 0;
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cpu_buffer = buffer->buffers[cpu];
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ret = cpu_buffer->entries;
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out:
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put_online_cpus();
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return ret;
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}
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@ -1629,17 +1617,13 @@ EXPORT_SYMBOL_GPL(ring_buffer_entries_cpu);
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unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu)
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{
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struct ring_buffer_per_cpu *cpu_buffer;
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unsigned long ret = 0;
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get_online_cpus();
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unsigned long ret;
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if (!cpumask_test_cpu(cpu, buffer->cpumask))
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goto out;
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return 0;
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cpu_buffer = buffer->buffers[cpu];
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ret = cpu_buffer->overrun;
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out:
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put_online_cpus();
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return ret;
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}
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@ -1658,16 +1642,12 @@ unsigned long ring_buffer_entries(struct ring_buffer *buffer)
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unsigned long entries = 0;
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int cpu;
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get_online_cpus();
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/* if you care about this being correct, lock the buffer */
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for_each_buffer_cpu(buffer, cpu) {
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cpu_buffer = buffer->buffers[cpu];
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entries += cpu_buffer->entries;
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}
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put_online_cpus();
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return entries;
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}
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EXPORT_SYMBOL_GPL(ring_buffer_entries);
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@ -1685,16 +1665,12 @@ unsigned long ring_buffer_overruns(struct ring_buffer *buffer)
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unsigned long overruns = 0;
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int cpu;
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get_online_cpus();
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/* if you care about this being correct, lock the buffer */
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for_each_buffer_cpu(buffer, cpu) {
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cpu_buffer = buffer->buffers[cpu];
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overruns += cpu_buffer->overrun;
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}
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put_online_cpus();
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return overruns;
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}
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EXPORT_SYMBOL_GPL(ring_buffer_overruns);
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@ -2093,21 +2069,16 @@ struct ring_buffer_event *
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ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts)
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{
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struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
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struct ring_buffer_event *event = NULL;
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struct ring_buffer_event *event;
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unsigned long flags;
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get_online_cpus();
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if (!cpumask_test_cpu(cpu, buffer->cpumask))
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goto out;
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return NULL;
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spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
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event = rb_buffer_peek(buffer, cpu, ts);
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spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
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out:
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put_online_cpus();
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return event;
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}
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@ -2189,17 +2160,15 @@ struct ring_buffer_iter *
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ring_buffer_read_start(struct ring_buffer *buffer, int cpu)
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{
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struct ring_buffer_per_cpu *cpu_buffer;
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struct ring_buffer_iter *iter = NULL;
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struct ring_buffer_iter *iter;
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unsigned long flags;
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get_online_cpus();
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if (!cpumask_test_cpu(cpu, buffer->cpumask))
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goto out;
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return NULL;
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iter = kmalloc(sizeof(*iter), GFP_KERNEL);
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if (!iter)
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goto out;
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return NULL;
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cpu_buffer = buffer->buffers[cpu];
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@ -2214,9 +2183,6 @@ ring_buffer_read_start(struct ring_buffer *buffer, int cpu)
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__raw_spin_unlock(&cpu_buffer->lock);
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spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
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out:
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put_online_cpus();
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return iter;
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}
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EXPORT_SYMBOL_GPL(ring_buffer_read_start);
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@ -2309,13 +2275,9 @@ void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu)
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{
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struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
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unsigned long flags;
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int resched;
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/* Can't use get_online_cpus because this can be in atomic */
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resched = ftrace_preempt_disable();
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if (!cpumask_test_cpu(cpu, buffer->cpumask))
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goto out;
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return;
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spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
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@ -2326,8 +2288,6 @@ void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu)
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__raw_spin_unlock(&cpu_buffer->lock);
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spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
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out:
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ftrace_preempt_enable(resched);
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}
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EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu);
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@ -2337,16 +2297,10 @@ EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu);
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*/
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void ring_buffer_reset(struct ring_buffer *buffer)
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{
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int resched;
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int cpu;
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/* Can't use get_online_cpus because this can be in atomic */
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resched = ftrace_preempt_disable();
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for_each_buffer_cpu(buffer, cpu)
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ring_buffer_reset_cpu(buffer, cpu);
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ftrace_preempt_enable(resched);
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}
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EXPORT_SYMBOL_GPL(ring_buffer_reset);
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@ -2359,8 +2313,6 @@ int ring_buffer_empty(struct ring_buffer *buffer)
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struct ring_buffer_per_cpu *cpu_buffer;
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int cpu;
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get_online_cpus();
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/* yes this is racy, but if you don't like the race, lock the buffer */
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for_each_buffer_cpu(buffer, cpu) {
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cpu_buffer = buffer->buffers[cpu];
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@ -2368,8 +2320,6 @@ int ring_buffer_empty(struct ring_buffer *buffer)
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return 0;
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}
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put_online_cpus();
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return 1;
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}
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EXPORT_SYMBOL_GPL(ring_buffer_empty);
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@ -2382,18 +2332,14 @@ EXPORT_SYMBOL_GPL(ring_buffer_empty);
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int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu)
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{
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struct ring_buffer_per_cpu *cpu_buffer;
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int ret = 1;
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get_online_cpus();
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int ret;
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if (!cpumask_test_cpu(cpu, buffer->cpumask))
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goto out;
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return 1;
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cpu_buffer = buffer->buffers[cpu];
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ret = rb_per_cpu_empty(cpu_buffer);
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out:
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put_online_cpus();
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return ret;
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}
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@ -2416,8 +2362,6 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
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struct ring_buffer_per_cpu *cpu_buffer_b;
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int ret = -EINVAL;
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get_online_cpus();
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if (!cpumask_test_cpu(cpu, buffer_a->cpumask) ||
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!cpumask_test_cpu(cpu, buffer_b->cpumask))
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goto out;
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@ -2466,8 +2410,6 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
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ret = 0;
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out:
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put_online_cpus();
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return ret;
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}
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EXPORT_SYMBOL_GPL(ring_buffer_swap_cpu);
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@ -2583,8 +2525,6 @@ int ring_buffer_read_page(struct ring_buffer *buffer,
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u64 save_timestamp;
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int ret = -1;
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get_online_cpus();
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if (!cpumask_test_cpu(cpu, buffer->cpumask))
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goto out;
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@ -2681,8 +2621,6 @@ int ring_buffer_read_page(struct ring_buffer *buffer,
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spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags);
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out:
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put_online_cpus();
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return ret;
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}
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